// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "ui/views/focus/external_focus_tracker.h"

#include "base/logging.h"
#include "ui/views/focus/view_storage.h"
#include "ui/views/view.h"

namespace views {

ExternalFocusTracker::ExternalFocusTracker(View* parent_view,
    FocusManager* focus_manager)
    : focus_manager_(focus_manager)
    , parent_view_(parent_view)
{
    DCHECK(parent_view);
    view_storage_ = ViewStorage::GetInstance();
    last_focused_view_storage_id_ = view_storage_->CreateStorageID();
    // Store the view which is focused when we're created.
    if (focus_manager_)
        StartTracking();
}

ExternalFocusTracker::~ExternalFocusTracker()
{
    view_storage_->RemoveView(last_focused_view_storage_id_);
    if (focus_manager_)
        focus_manager_->RemoveFocusChangeListener(this);
}

void ExternalFocusTracker::OnWillChangeFocus(View* focused_before,
    View* focused_now)
{
    if (focused_now && !parent_view_->Contains(focused_now) && parent_view_ != focused_now) {
        // Store the newly focused view.
        StoreLastFocusedView(focused_now);
    }
}

void ExternalFocusTracker::OnDidChangeFocus(View* focused_before,
    View* focused_now)
{
}

void ExternalFocusTracker::FocusLastFocusedExternalView()
{
    View* last_focused_view = view_storage_->RetrieveView(last_focused_view_storage_id_);
    if (last_focused_view)
        last_focused_view->RequestFocus();
}

void ExternalFocusTracker::SetFocusManager(FocusManager* focus_manager)
{
    if (focus_manager_)
        focus_manager_->RemoveFocusChangeListener(this);
    focus_manager_ = focus_manager;
    if (focus_manager_)
        StartTracking();
}

void ExternalFocusTracker::StoreLastFocusedView(View* view)
{
    view_storage_->RemoveView(last_focused_view_storage_id_);
    // If the view is NULL, remove the last focused view from storage, but don't
    // try to store NULL.
    if (view != NULL)
        view_storage_->StoreView(last_focused_view_storage_id_, view);
}

void ExternalFocusTracker::StartTracking()
{
    StoreLastFocusedView(focus_manager_->GetFocusedView());
    focus_manager_->AddFocusChangeListener(this);
}

} // namespace views
